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Rewrote description of return value. 

As per http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=296183
This commit is contained in:
Michael Kerrisk 2005-06-16 15:07:57 +00:00
parent 4f90a5f34e
commit 2a01941630
1 changed files with 25 additions and 13 deletions
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38
man2/nice.2
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@ -28,7 +28,7 @@
.\" Modified 2001-06-04 by aeb
.\" Modified 2004-05-27 by Michael Kerrisk <mtk-manpages@gmx.net>
.\"
.TH NICE 2 2004-05-27 "Linux 2.6.6" "Linux Programmer's Manual"
.TH NICE 2 2005-06-16 "Linux 2.6.12" "Linux Programmer's Manual"
.SH NAME
nice \- change process priority
.SH SYNOPSIS
@ -36,14 +36,15 @@ nice \- change process priority
.sp
.BI "int nice(int " inc );
.SH DESCRIPTION
.B nice
.BR nice ()
adds
.I inc
to the nice value for the calling pid.
(A large nice value means a low priority.)
Only the super\%user may specify a negative increment, or priority increase.
.SH "RETURN VALUE"
On success, zero is returned. On error, \-1 is returned, and
On success, the new nice value is returned (but see NOTES below).
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
@ -59,21 +60,32 @@ capability is required.
.SH "CONFORMING TO"
SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3. However, the Linux and glibc
(earlier than glibc 2.2.4) return value is nonstandard, see below.
SVr4 documents an additional
EINVAL error code.
SVr4 documents an additional EINVAL error code.
.SH NOTES
Note that the routine is documented in SUSv2 and POSIX 1003.1-2003
to return the new nice value, while the Linux syscall and (g)libc
(earlier than glibc 2.2.4) routines return 0 on success.
The new nice value can be found using
SUSv2 and POSIX 1003.1-2003 specify that
.BR nice ()
should return the new nice value.
However, the Linux syscall and the
.BR nice ()
library function provided in older versions of glibc
(earlier than glibc 2.2.4) return 0 on success.
In this case, the new nice value can be found using
.BR getpriority (2).
Note that an implementation in which
.B nice
returns the new nice value can legitimately return \-1.
Since glibc 2.2.4,
.BR nice ()
is implemented as a library function that calls
.BR getpriority (2)
to obtain the new nice value,
and this is returned to the caller as the function result of the
.BR nice ()
call.
With this implementation,
a successful call can can legitimately return \-1.
To reliably detect an error, set
.I errno
to 0 before the call, and check its value when
.B nice
.BR nice ()
returns \-1.
.SH "SEE ALSO"
.BR nice (1),